Skia Build

Drift uses libdrift_skia.a, which combines Skia with the Drift bridge code. The bridge is pre-compiled at CI/build time, so app developers using prebuilt binaries don't need Skia headers - only the skia_bridge.h header included in the drift module. Building from source still requires a full Skia checkout.

The drift CLI searches for libraries in these locations (in order):

1. <drift_module>/third_party/drift_skia/ - source builds take priority
2. <project>/third_party/drift_skia/ - project-local customization
3. ~/.drift/drift_skia/ - downloaded prebuilt binaries (fallback)

Skia source is still checked out under third_party/skia; build outputs are copied into third_party/drift_skia/.

The library paths (relative to any of the above locations) are:

• Android: android/<arch>/libdrift_skia.a
• iOS device: ios/<arch>/libdrift_skia.a
• iOS simulator: ios-simulator/<arch>/libdrift_skia.a

Supported architectures:

Platform	Architectures
Android	arm64, arm, amd64
iOS device	arm64
iOS simulator	arm64, x64

Automatic Download (Recommended)

Skia libraries are automatically downloaded when you run drift build for the first time. No manual setup is required for most users.

When you run drift build, missing Skia libraries are automatically downloaded:

drift build android    # auto-downloads Android libraries if missing
drift build ios        # auto-downloads iOS libraries if missing

To disable auto-download and fail with an error instead:

drift build android --no-fetch

Fetch via CLI

You can manually download libraries using the fetch-skia command:

drift fetch-skia              # fetch all platforms
drift fetch-skia --android    # android only
drift fetch-skia --ios        # ios only
drift fetch-skia --version v0.2.0  # specific version

The command downloads tarballs from https://github.com/go-drift/drift/releases, verifies SHA256 checksums, and extracts them to ~/.drift/lib/<version>/.

Version is determined automatically from the CLI version, or you can set DRIFT_VERSION environment variable or use the --version flag.

Build from Source

Building from source is intended for drift contributors or users who need custom Skia builds. Most app developers should use the prebuilt binaries.

For source builds, you need a writable checkout of the drift repository:

git clone https://github.com/go-drift/drift.git
DRIFT_SRC=$PWD/drift

Building from source requires:

• Python 3
• Ninja build system
• For Android: ANDROID_NDK_HOME environment variable set

Fetch Skia Source

$DRIFT_SRC/scripts/fetch_skia.sh

This clones Skia from https://skia.googlesource.com/skia, checks out the latest main, and runs git-sync-deps to fetch dependencies.

Build for Android

export ANDROID_NDK_HOME=/path/to/android-ndk
$DRIFT_SRC/scripts/build_skia_android.sh

Builds libdrift_skia.a for arm64, arm, and amd64 using NDK API level 21 with OpenGL ES support. The script compiles Skia, then compiles the drift bridge and combines them into a single static library. Output is written to third_party/drift_skia/android/.

Build for iOS

Requires macOS with Xcode command line tools (the script uses xcrun and libtool).

$DRIFT_SRC/scripts/build_skia_ios.sh

Builds libdrift_skia.a for:

• Device: arm64
• Simulator: arm64 (Apple Silicon), x64 (Intel)

Uses Metal for GPU rendering. The script compiles Skia, then compiles the drift bridge and combines them using libtool. Output is written to third_party/drift_skia/ios/ and third_party/drift_skia/ios-simulator/.

Build for iOS using xtool (Linux)

If you have xtool set up for iOS development on Linux, you can cross-compile Skia without macOS:

$DRIFT_SRC/scripts/build_skia_xtool.sh

The script auto-detects the iOS SDK from ~/.xtool/sdk/iPhoneOS.sdk (set up via xtool setup) and uses the system clang with --target flags for cross-compilation. It creates wrapper scripts to translate Skia's macOS-style -arch flags.

Requirements:

• xtool with iOS SDK (xtool setup /path/to/Xcode.xip)
• System clang (14+)
• Python 3, Ninja

Output is written to third_party/drift_skia/ios/. Simulator builds are skipped if iPhoneSimulator.sdk is not present.